The present invention relates to a centrifugal type counterflow contact apparatus for use with a centrifugal extractor in which extraction is effected by the counterflow contact of heavy and light liquids insoluble to each other.
The prior centrifugal type counterflow contact apparatus disclosed in Japanese Utility Model Publication No. 12767/1978 and Japanese Patent Publication No. 12564/1961 employs a plurality of perforated cylinders coaxially disposed and spaced from one another within a rotary drum. With such arrangement, a heavy liquid is introduced to the center of the rotary body or drum while a light liquid is introduced about the periphery thereof. The rotation of the rotary body or drum causes the radial counterflow of the heavy and light liquids. That is, the heavy liquid is caused to flow radially outwardly through the pores or small holes in the perforated cylinders while the light liquid is caused to flow radially inwardly through them while making the counterflow contact with the heavy liquid.
The centrifugal type counterflow contact apparatus disclosed in Japanese Patent Publication No. 24283/1967 employs a plurality of perforated rings each having a frustoconical configuration in cross-section and disposed within the rotary body or drum. The wall of each perforated ring is inclined at a small acute angle relative to the horizontal in a plane including the axis of the rotary drum. The walls of adjacent rings alternately diverge and converge toward the one side wall of the rotary drum. With such construction, the heavy and light liquids counterflow contracting each other at areas where adjacent rings are close to each other, and are separated from each other at areas where adjacent rings are spaced away from each other.
In both of the centrifugal type counterflow contact apparatus described above, sludge or solids entrained in the feed are accumulated on the inner or outer surfaces of the perforated rings or cylinders depending upon the specific gravity of the solids, so that extraction efficiency of the apparatus is decreased. The accumulated solids may be washed away from outside by removing rotary plugs on the peripheral wall of the rotary body or drum. However, this cleaning method is difficult to be completely done. Furthermore the nonuniform distribution of the solids still remaining in the rotary body or drum after cleaning frequently causes dynamic imbalance of the rotary body or drum, resulting in a serious accident during operation.